System of control for synchronous motors driving through clutches



, Nov. 20, 1923. 4

- 4 R. l. MAUJER SYSTEMOF CONTROL FOR SYNCHRONOUS MOTORS .DRIVING THROUGH CLUTCHEjS Filed'July a, 1922 IN V EN TOR.

ATTORNEY Patented Nov. 20, 1923.

UNITED STATES 1,474,97 PATENT OFFICE.

ROBERT I. MAUJER, OF CINCINNATI, OHIO, ASSIGNOR TO THE CUTLER-HAMMER MFG.

00., OF MILWAUKEE, WISCONSIN, A CORPORATION OF, WISCONSIN.

SYSTEM OF CONTROL FOR SYNCHRONOUS MOTORS DRIVING THROUGH CLUTCHES.

Application filed July 8,

To all whom it may concern: 7

Be it known that I, ROBERT I. MAUJER, a citizen of the United States, residing at Cincinnati, in the county of Hamilton and State of Ohio, have invented new and useful Improvements in Systems of Control forSynchronous Motors Driving Through Clutches, of which the following is a full, clear, concise, and exact description, reference being 10 had to the accompanying drawing, forming apart of this specification.

This invention relates to systems of control for synchronous motors driving through clutches or other releasable connections.

Synchronous motors may be designed for a relatively high starting torque but the same will not ull into step if loaded. For this reason it iias heretofore been the usual practice to first synchronize the motor and then accelerate its load through the medium of a friction clutch. It is necessa to effect radual acceleration of the loa and in practlce it has been found that the slippage between the clutch surface tends to produce rapid deterioration thereof. It has also been found that the clutch must be of relatively large capacity in proportion to the load in order to start the same in this manner..

The present invention has among its objects to provide a control system for synchronous motor drives wherein provision is made for connecting a load of high inertia to the motor during starting of the latter and for temporarily disconnecting the load from the motor to permit the latter to pull into step. Another object is to provide an automatic controller adapted to automatically establish starting and running connections for the synchronous motor and to also efiect automatic control of the clutch in the manner aforestated.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing diagrammatically illustrates an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification with-4 0 out departing from the scope of the appended claims.

In the drawing, M indicates a synchronous motor having a stator provided with the usual armature windings to be supplied 1922. Serial No. I 573,664.

with current from a three phase supply circu1t indicated by lines L, L and L and a rotor having theusual field windings to be supplied with current from a suitable source such as a battery B. Motor M isiradapted to be connected to a high inertia load such as a fan E through the medium of a clutch C, said'clutch being of a conventional magnetic type.

The controller includes a 5-pole electromagnetic switch 1 adapted to establish starting connections for the motor through com pensator windings 2 and 3,'a 3-pole electromagnetic switch 4 for establishing running connections therefor, and two single pole electro-magnetic switches 5 and 6 for connecting the field of the motor to battery B, the former switch having contacts'5 associated therewith for normally including a field resistance R. The controller also includes a 2-pole electro-magnetic switch 7 for establishing an energizing circuit for clutch C from battery B.

The control means for the aforedescribed switches includes a double pole electro-magnetic switch 8 and electro-magnetic relays 9 and 10. Switch 8 is controlled by a sna switch 8 and as hereinafter set forth sa-i switch supplies current from a transformer T for energization of the operatin windings of starting switch 1, running switc 4, clutch control switch 7 and relays 9 and 10. Relay 9 is of the dash pot retarded type, the dash pot thereof being arranged to permit quick upward movement ofmovable contact member 9" and to retard downward movement of said member. Contact member 9 normally engages a contact 9 connected in the energizing circuit of clutch control switch 7 and upon movement thereof out of normal posi tion the same engages contacts 9 and 9, the contact 9 being connected in the energizing circuit of said clutch control switch and the contact 9 being connected in the energizing circuit of starting switch 1. Relay 10 is provided with normally closed contacts 10 and normally open contacts 10 and 10. Contacts 10 control the energizing circuit of relay 9 and contacts 10 serve to establish a maintainin circuit for the operating winding of re ay 10 and also serve to establish an ener izing circuit for running switch 4 throng the medium of normally closed auxiliary contacts- 1 associated with starting switch 1. Contacts 1O control the.

energizin circuits of field switches 5 and 6 through t e medium of an auxiliar switch 7 associated with switch 7 and fiel control switch 6 is provided with auxiliary contacts 6 for maintaining itself and switch 5 through contacts 10.

The operation and circuit connections of the aforedescribed controller will now be more fully set forth. Closure of switch 8% establishes an energizing circuit for switch 8 extending from the upper terminal of the secondary winding of transformer T; through said switch, through the winding of switch 8 to the lower terminal of said secondary winding, and upon closure of switch 8 the upper terminal of said secondary winding is connected to conductor 15 and the lower terminal thereof is connected to conductor 16. Immediately upon closure of switch 8 relay 9 is energized by a circuit extending from conductors 15 to 17 through the operating winding of said relay by conductor 18 through the normally closed contacts 10 of relay 10 and by conductor 19 to conductor 16. Relay 9 thereupon responds to establish an energizing circuit for starting switch 1 extending from conductor 15 by conductor 20 through the operating winding of starting switch 1 by conductor 21 to contact 9 through movable contact member 9 and by conductor 22 to line 16. Response of relay 9 also establishes an energizing ircuit for the clutch control switch 7 extend ng from conductor 15 through the winding of said switch by conductors 23 and 24 to contact 9 and through the movablecontact member 9 and conductor 22 to conductor 16. Closure -is accelerated through the medium of clutch C.

Immediately upon closure of starting switch 1, the auxiliary contacts 1 thereof establish an energizing circuit for relay 10 extending from conductor 15 by conductor 25 through the winding of saidvrelay by conductor 26 through auxiliary contacts 1 and by conductor 27 to conductor 16. In responding reiay l0 interrupts the energizing circuit for timing relay 9, extending through the contacts 10 thereof and establishes a maintaining circuit for its winding extending from conductors 15 and 25 through said winding as by conductor 28 through contacts'lO and by conductor 29 to conductor 16. Upon de-energization of relay '9 the movable contact element thereof disengages contacts 9 and 9 to de-energize starting switch 1 and clutch control switch 7 and upon opening of startingswitch 1, running extending from the right hand terminal of battery B by conductor 32 through contacts 10 by conductor 33 through contacts 7 of switch 7 by conductors 3 1 and 35 through the operating windings of switches 5.and'6 in parallel and by conductor 36 to the left hand terminal of the battery B. Thus provision is-made for establishing running con nections for the motor and for simultaneously de-energizing clutch C upon establishment of such" connections to unload the m0- tor and permit the same to pull into step. Relay 9 is calibrated so that the same does not return to normal position until the motor pulls into step and upon return of the contact member 9 to normal position the aforedescribed energizing circuit for clutch control switch 7 is re-established through contact 9 and upon closure of said switch clutch C is again energized to bring load E up to synchronous speed. Upon response of switch 7, field control switch 6 maintains itself and also field control switch 5 in closed position through a circuit extendin from the right hand terminal of battery to conductor 33 as already traced by conductor 37 through auxiliary switch 6 of switch 6 by conductors 38 and 35 through the windings of said fieldiswitches in parallel and by conductor 36 to the left hand terminal of battery B.

Opening of push button switch 8 de-energizes switch 8 and said switch in opening de-energizes relay 10 to interrupt the aforedescribed energizing circuits of running switch' l, field control switches 5 and 6 and the clutch of control switch 7. The motor thereupon comes to rest, the current in the field being discharged through resistance R and switch 5 of field switch 5.

What I claim as new and desire to secure by Lettersllaatent is:

1. The combination with a synchronous motor, and a releasable driving connection therefor, of means for starting said motor and means for establishing said driving connection during starting of said motor andfor temporarily releasing the same as I the speed of said motor approaches syn- P- I A '2. The combination with a synchronous chronism' to permit said motor to came into motor, of an electromagnetic clutch-for es tablishing driving connections. therefor,

means for establishing startin and running connections for saldmotor an control meansfor said clutch adapted to eifect engagement thereof upon establishment of startlng connections and to effect" disengagement thereof fora temporary period upon establishment of. running connections to per-'. mit said-motor to come into st'ep.

The combination with synchronous motor and an electro-magnetic clutch forestablishing driving connections therefor,

switches for establishing-starting and run-. ning connections for said motor, control means 'for said switches insuring establishment of starting connection prior to establishment of running connections and establisl-iment of running connections upon in- 'terruption of starting connections and means associated with said former' means for effecting engagement of said clutch upon establishment of starting connections and disengagement thereof for a temporary period uponestablishment' of running connections.

' 4. The combinationwitha synchronous motor and an electro-magnetic clutch for establishing driving connections therefor,

.electro respon sive switches for establishing starting and running connections for said eluding a. timing relay adapted to insure,

to establishment of running connectionsand establishment of running connections .upon

interruption of starting connections and control means for said clutch associated with said timing: relay' to effect. engagement of motor control means for said switches inestablishment of startin "connections prior saidclutch up'on establishment of starting 1 connections. and disengagement of said including a timing relay responsive to es-' tablish starting connections and adapted when -de-energize to interrupt said starting connections and establish running connec-.

tions,and control means for said clutch associated with said relay to effect engage-- ment of said clutch npon response of said relay and disengagement of said clutch for. a temporary period. during'return of said relay to normal position.' 1

scribed-my name.

. ROBERT. I. MAUJER.

In witness whereof, I have hereunto sub- '45 -clutch for a temporary period upon estab 

